READ TOTALIZER 1, TOTALIZER 2 AND Absolute Volumeflow FROM MAG 5100W to S7-1200

1) I assume that you are using the MAG 6000 converter (electronic box) on a 5100W tube. Correct?

2) Do you have the manual cited below? (the other Modbus document is the Quick Start)

Manuals SITRANS F MODBUS RTU RS 485 add-on module for transmitter types SITRANS F M MAG 5000/6000 and SITRANS F C MASS 6000
Edition: 3
Operating Manual
Document identification number: SFIDK.PS.023.D3.02
Part number of the documentation: FDK:521H1183
2006-09-05
ID: 18238830

3) >right now I can read the
address slave ID number located at address 600 (register 00601), 2 bytes
TAG "flowmeter" located at address 640 (register 00641), 18 bytes
Baud rate located at register; address 529 (register 400530), 2 bytes, bit coded

4) The data read above is byte data or bytes in a string.

Look at the process data table with Modbus register addressing at the top of page 14 pdf of the Modbus manual for the process data you seek.

The word formats for process data are either double longs or floats. Since the volume is available only in floating point, why not stay with floating point for all the values?

- TOTALIZER 1, 4 bytes or two floating point words, located at address 3022
- TOTALIZER 2, 4 bytes or two floating point words, located at address 3024
- Absolute Volumeflow, 4 bytes, or two floating point words, located at 3002

Use the same 03H "read holding register" instruction to read the addresses above and you'll fetch the process data values. But you'll have to interpret the data as floating point.